CODEWITHSUNDEEP
cloopsswitch-statementinfinite-loop
Sparky3295
Sparky3295

Reputation: 19

C Program, Switch menu endless loop

Okay It now loops correctly but when you give it an input e.g. '2' it just goes to the default case.

 print_Menu() {
        while ( 1 )
    {
        printf("=============================================\n");
        printf("MENU\n");
        printf("=============================================\n");
        printf("1. Do stuff\n2. Do more stuff\n3. Do even more stuff\n4. Quit\n");
        printf("Choose an option: ");

        scanf(" %s*", &selection);


        switch (selection) {
            case 1:
                /*do your thing for option 1*/
                printf("thing 1\n");
                break;
            case 2:
                /*do your thing for option 2*/
                printf("thing 2\n");
                break;
            case 3:
                /*do your thing for option 3*/
                printf("thing 3\n");
                break;
            case 4:
                /*do your thing for option 3*/
                printf("quiting app\n");
                exit(0);
                break;
            default:
                printf(" Invalid selection\n");
               // print_Menu();
                break;
        }
      }

Upvotes: 0

Views: 7579

Answers (2)

Spikatrix
Spikatrix

Reputation: 20244

Just add 

scanf("%*s");

in the default case to clear the invalid character(s) from the input buffer.The * tells scanf to scan a string and then discard it.

scanf fails to get an integer and returns 0 when you enter any other thing other than an integer. This data does not get consumed by the scanf and hence, remains in the stdin.When scanf is called for the second time,it sees the character which you typed in earlier and then again fails to read an integer.This will then result in an infinite loop

Upvotes: 3

BLUEPIXY
BLUEPIXY

Reputation: 40145

if(1!=scanf("%d", &selection)){
    while(getchar() != '\n');
    selection = -1;
}

Upvotes: 0

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